Device for determining at least one parameter of a flowing medium

ABSTRACT

A device for determining at least one parameter of a flowing medium. The device including an element, for example in the form of a bulge, in the channel in which the measuring element is positioned, which deflects the foreign particles and thus protects the measuring element.

This application is a 371 of PCT/DE01/03258 Aug. 25, 2001.

FIELD OF THE INVENTION

The present invention relates to a device for determining at least oneparameter of a flowing medium.

BACKGROUND INFORMATION

A device including a measuring channel is referred to in GermanPublished Patent Application No. 197 35 891, which houses a measuringelement around which the medium entering flows. The measuring channel isslanted at a selected angle in relation to a lengthwise axis of theline, so that the inlet channel includes a region shadowed from a mainflow direction. The measuring element is positioned in the shadowedregion of the measuring channel in order to avoid fouling and resultingdefects of the measuring element.

As a consequence of water entering the intake line, e.g., due to aroadway wet with rain, or the entry of particles, contamination of themeasuring element may occur. Natural dissolved salt components containedin this splashed water then produce drift of the characteristic of themeasuring element as a consequence of the formation of saltencrustations on the membrane of the sensor part. The particles maydamage or even destroy the measuring element. A protected region isformed by the slant of the measuring body, but liquids or particlesreach the measuring channel regardless.

A hot-wire airflow meter, referred to in German Published PatentApplication No. 197 38 337 and U.S. Pat. No. 5,892,146, includes a bulgeupstream from the measuring element which is configured in one piecewith a wall of the line. This bulge is not configured in a measuringchannel and is not used to deflect liquids or particles.

A measuring device is referred to in German Published Patent ApplicationNo. 198 15 654, in which a measuring channel includes a bulge whichprotects the measuring element from particles. However, this bulge isnot used to deflect liquids or particles, so that they may continue toarrive in the channel.

A device is referred to in German Published Patent Application No. 19735 664 and GB Patent No. 232 85 14, in which the measuring element ispositioned inside a tubular body which the medium flows through, anupstream end of the tubular body extending into a filter chamber andincluding inlet openings on a lateral surface there, in order to reducethe impingement of dirt particles or water droplets on the measuringelement. Particularly in the event of very polluted air and a highproportion of water in the intake air of the internal combustion engine,there is the danger of the air filter being soaked with water, whichthen penetrates through the filter mat and carries along dirt particlesat the same time. On the downstream side of the air filter, the actualclean side, the danger arises as a consequence that the intake air againpulls along dirt particles and water droplets from the filter surface,which are then deposited in an undesired manner on the measuring elementand result in erroneous measurements or failure of the measuringelement. The tubular body of other prior systems reduces the danger ofdeposits on the measuring element through the arrangement of inletopenings on the lateral surface, however, a correspondingly longconfiguration of the tubular body causes an undesired pressure drop,which results in reduction of measuring sensitivity. In addition, thereduction of impingement of the measuring element with liquid/solidparticles may hardly be ensured at a very high liquid intake ofapproximately 20 liters/hour.

During the operation of the device, it may occur that, for example, oildroplets or oil vapor are carried along in the air against the main flowdirection and the measuring element is contaminated, which significantlyworsens the measuring properties. Reasons for the backflow of liquidsare, for example, pulsating flows or running on of a turbo charger inthe shutdown phase. The inner surface of a protective grid, which isconfigured including a special wide mesh, is not sufficient as acondensation surface for the liquid.

SUMMARY OF THE INVENTION

The exemplary device according to the present invention includes atleast one measuring element protected from the impingement of liquidsand particles.

A channel includes a bulge upstream from the measuring element, whichdeflects the liquids and particles carried along in the medium and thusprotects the measuring element from contamination.

The channel includes a rejection grid upstream from the measuringelement, which deflects the liquid and particles flowing in and thusprotects the measuring element from contamination.

Furthermore, the channel includes an outlet opening for the liquids andparticles between the element for deflecting liquids and particles andthe measuring element, so that they leave the channel and may no longercontaminate the measuring element.

The channel includes an indentation, because in this manner thedeflected liquids and particles are collected and flow resistance in thechannel is not increased.

A starting region of the channel is arranged such that it is radiallyoffset, this protects the measuring element from the liquids andparticles.

Through an oil rejection grid in at least one opening of the channel,oil may be prevented from penetrating the channel and damaging themeasuring element.

For manufacturing the device the channel is configured in two parts and,for example, an attachable sleeve is used as one part.

Negative influence of pulsating airflow, i.e., backflows in the line, onthe measuring behavior of the measuring element may be reduced by apulsation channel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a device for determining at least one parameter of aflowing medium in the installed state.

FIG. 2 shows an inlet, deflection, and outlet channel in a measuringhousing of the exemplary device according to the present invention.

FIG. 3 shows a section along line III—III of FIG. 2 for a firstexemplary embodiment of the present invention.

FIG. 4 shows a section along line IV—IV of FIG. 2 for a second exemplaryembodiment of the present invention.

FIG. 5 shows a section along line V—V of FIG. 2 for a third exemplaryembodiment of the present invention.

FIG. 6 a shows a section along line VI—VI of FIG. 2 for a fourthexemplary embodiment of the present invention.

FIG. 6 b shows a section along line VI—VI of FIG. 2 for a fifthexemplary embodiment of the present invention.

FIG. 7 shows a section along line VII—VII of FIG. 2 for a sixthexemplary embodiment of the present invention.

FIG. 8 shows a further exemplary embodiment of the present invention.

DETAILED DESCRIPTION

FIG. 1 schematically shows how a device 1 is installed in a line 2, inwhich the medium to be measured flows. Device 1 for determining at leastone parameter includes a measuring housing 6, identified by a lowerrectangle indicated by a dot-dash line, and a carrier part 7, identifiedby an upper rectangle indicated by a dot-dash line, in which, forexample, analyzing electronics are housed. In this exemplary embodimentof device 1, a measuring element (FIG. 2) is used, which, for example,determines the volume rate of flow of the flowing medium. Furtherparameters which could be measured are, for example, the pressure, thetemperature, a concentration of a medium component, or a flow speed,which may be determined using suitable sensors.

Measuring housing 6 and carrier part 7 have a shared longitudinal axis8, which runs in the direction of installation and may, for example,also be the center line. Device 1 is, for example, pluggably insertedinto a wall 5 of line 2. Wall 5 delimits a flow cross-section of line 2,in whose center a center line 4 extends in the direction of the flowingmedium parallel to wall 5. The direction of the flowing medium, referredto in the following as the main flow direction, is identified bycorresponding arrows 3 and runs from left to right in this case.

FIG. 2 shows an exemplary embodiment of measuring housing 6 including achannel 20 without a cover (not shown) which closes channel 20. Channel20 is formed by a floor part 42 and a cover. Main flow direction 3 ofthe medium is indicated by arrows. Channel 20 includes, for example, aninlet channel 13, into which the flowing medium flows, a deflectionchannel 15, into which the flowing medium is deflected, and an outletchannel 19. Flow directions 25, 26 in inlet channel 13 and outletchannel 19 are also identified by arrows. An inlet channel centerline 23is curved here, for example, since edge surfaces 35 of inlet channel 13have a streamlined configuration. Outlet channel centerline 22 is, forexample, a straight line here. Channel 20 may also be configured withoutthe deflection channel and outlet channel, for example as a channelcurved slightly from inlet opening 11 in main flow direction 3 or acontinuous straight channel. Any other channel shape is conceivable,even a course perpendicular to longitudinal axis 8.

In a forward region 39 of channel 20 before inlet opening 11, throughwhich the medium flows in, a flow obstruction 24 is provided, forexample, which causes defined flow separation which is effective in thechannel.

A bow 69 of measuring housing 6 is shaped, for example, so that solid orliquid particles are reflected away from inlet opening 11. For thispurpose, bow 69 is slanted in the opposite direction to support part 7.In deflection channel 15, an edge surface 40 is, for example, slanted byan angle δ against main flow direction 3. Angle δ may be in the range ofapproximately 30 to 60°, but is ideally approximately 45°. Edge surface40 has a width br, which corresponds to at least two-thirds of width bof inlet opening 11 of inlet channel 13. Furthermore, an opening 18 is,for example, provided in deflection channel 15 which establishes aconnection to a medium flowing around device 1. There may also bemultiple openings. The opening(s) may be located on side walls 41 and/orlead to a lower outer surface 21 of measuring housing 6 of device 1including channel 20, in order to establish the connection to line 2,through which the pulsation behavior is i.e., the device measuresprecisely even in the event of pulsating media disturbances. At the endof outlet channel 19, an outlet opening 12, through which the mediumleaves channel 20 again, is located, whose surface forms, for example,an angle δ to main flow direction 3. Outlet opening 12 has, for example,a larger cross-section than outlet channel 19, through which thepulsation behavior is improved. At least one measuring element 10 is,for example, housed in a sensor carrier 9, which projects into inletchannel 13. The part of channel 20 in which measuring element 10 islocated is also referred to as measuring channel 17.

The configuration of a measuring element 10 is referred to in GermanPublished Patent Application No. 195 24 634.

FIG. 3 shows a section along line III—III of FIG. 2. A medium flows inmain flow direction 3 which, in addition to gas components, such as air,may also contain other components such as liquid particles 50 or dustparticles. If these particles reach measuring element 10, they maydamage it. In order to prevent this, an element 55 for particledeflection is positioned upstream from measuring element 10. Element 55may, for example, be an inlet nozzle, not shown, in wall 5, which blowsair in at this location and thus deflects the air flowing in toward theopposite wall, so that it may no longer reach measuring element 10.

In this exemplary embodiment, element 55 is a bulge 60. Liquid particles50 and other particles flowing in main flow direction 3 hit this bulge60, which at least partially shadows measuring element 10 in main flowdirection 3, and the particles deflect so that they move past measuringelement 10 or even leave channel 20 upstream from measuring element 10through, for example, a particle outlet opening 67 provided. A liquidwall film 61 partially forms on bulge 60, which breaks away at thesummit of the bulge as a large drop due to the flow in inlet channel 13and, for example, is carried along into an indentation 63 of inletchannel 13 present in an edge surface 35 lying approximately oppositebulge 60. Indentation 63 is, for example, approximately matched to theouter shape of bulge 60. A liquid wall film 61 also forms in indentation63, which moves forward along edge surface 25 downstream toward themedium flow. Downstream from indentation 63, but at least before or atthe same axial length as measuring element 10, particle outlet opening67 is located, for example, through which the particles, particularlyliquid particles 50, may leave inlet channel 13 again. Measuring element10 is thus protected from the impingement of particles. In this case,particle outlet opening 67 is positioned between a flat region of wall35 and a curved region of wall 35. The particles also partially leaveinlet channel 13 directly after deflection by element 55 or by bulge 60.A flow surface of bulge 60 directed against the medium flows forms anangle of intersection β with main flow direction 3. Indentation 63 formsan angle of intersection a with main flow direction 3. The angles ofintersection are in the range from 0 to 90°, i.e., bulge 60 and/orindentation 63 are configured slanted in main flow direction 3.

FIG. 4 shows a section along line IV—IV of FIG. 2. This exemplaryembodiment corresponds to that of FIG. 3 up to the position of particleoutlet opening 67. Indentation 63 includes a saddle point 71, which hasthe greatest distance to a plane which is formed by center line 4 andlongitudinal axis 8 and in which measuring element 10 is situated.Outlet opening 67 may be positioned at any location between saddle point71 and a downstream end of measuring element 10. Particle outlet opening67 is positioned within a curved region of wall 35 here.

At least one tapering element 73 is, for example, positioned atapproximately the same axial height as measuring element 10 in inletchannel 13, which causes acceleration of the flowing medium andstabilization of the measuring behavior of measuring element 10.

FIG. 5 shows a section along line V—V of FIG. 2 for a further exemplaryembodiment.

Wall 35 of inlet channel 13 runs, up to a transition region 79, parallelto a plane which is formed by center line 4 and longitudinal axis 8 inthis case. Inlet channel 13 includes a forward region 75 which isdisplaced, in relation to a rear region 77 of inlet channel 13, by adistance d in a direction perpendicular to center line 4 andlongitudinal axis 8 in such a manner that bulge 60 shields measuringelement 10 even more. Transition region 79, in which at least oneparticle outlet opening 67 is implemented on the side of edge surface 35lying opposite bulge 60, is located between forward region 75 and rearregion 77.

FIG. 6 a and FIG. 6 b show further exemplary embodiments of the presentinvention. For example, two elements 55 for particle deflection arepositioned in channel 20. There may also be more elements 55 present.Elements 55 are, for example, each formed by a bulge 60. Bulges 60 are,for example, positioned on opposing edge surfaces 35 of channel 20 andone after another in flow direction 3. At least one particle outletopening 67 is, for example, provided for each bulge 60 in wall 5,through which the foreign particles, particularly liquid particles 50,may reach line 2.

FIG. 6 b shows a further variant of FIG. 6 a. In this case, elements 55are positioned at approximately the same axial height in channel 20.Correspondingly, the two particle outlet openings 67 are positionedopposite one another.

FIG. 7 shows a further exemplary embodiment of the present invention.

Channel 20 is formed of a first part 80 and a second part 82, secondpart 82 may be formed by measuring housing 6. First part 80 is, forexample, formed by a sleeve 84 made of metal or plastic, which may, forexample, be slipped or glued onto measuring housing 6. Sleeve 84includes, for example, on the front end situated upstream, a rejectiongrid 88 as an element 55 for particle deflection. Rejection grid 88deflects foreign particles such as liquid particles 50 so that they aredeflected in the direction toward a wall of sleeve 84 and leave channelthrough a particle outlet opening 67 or are deflected past measuringelement 10. Two channels 20, 20′ are formed by sleeve 84. Channel 20′ isdelimited in relation to channel 20 by a dot-dash line and runs, forexample, between an outer wall 86 of measuring housing 6 and wall 35 ofchannel 20′.

Rejection grid 88 is referred to in German Published Patent ApplicationNo. 199 42 502.

FIG. 8 shows a further exemplary embodiment of the present invention. Incontrast to FIG. 2, outlet opening 12 of outlet channel 19 is adjoinedby, for example, a pulsation channel 92. Pulsation channel 92 improvesthe measuring behavior of measuring element 10 during pulsations arisingin line 2. The flowing medium leaves pulsation channel 92 in, forexample, the direction of main flow direction 3. An oil condensationgrid 94 is, for example, positioned in the region of a downstream end ofpulsation channel 92, which prevents oil from being able to reachchannel 20 in the event of backflows. This occurs in that the oilprecipitates on appropriately large grid inner surfaces of the wallsforming the grid openings.

One or more oil condensation grids 94 may also be positioned in eachother inlet opening 11 or outlet opening 12, 67.

1. A device for determining at least one parameter of a medium, themedium including a gas-particle mixture of intake air for an internalcombustion engine and flowing in a line along a main flow direction, thedevice comprising: a measuring housing arranged in the line; at leastone channel arranged in the measuring housing and formed by edgesurfaces that completely surround the channel; at least one measuringelement located in the at least one channel, surrounded by the edgesurfaces of the channel, and around which the medium flows; and at leastone deflecting element to deflect particles and liquids that is arrangedin the measuring housing on at least one of the edge surfaces of thechannel, upstream from the measuring element.
 2. The device of claim 1,wherein the at least one deflecting element is formed by at least onebulge.
 3. The device of claim 2, wherein the at least one bulge forms anangle of intersection between 90° and 0° with the main flow direction.4. The device of claim 1, further comprising: at least one outletopening in at least one of the edge surfaces of the channel for theparticles and the liquids, and arranged between the at least onedeflecting element and the at least one measuring element.
 5. The deviceof claim 1, wherein at least one of the edge surfaces of the at leastone channel includes an indentation pointing outward at approximately asame axial length as that of the at least one deflecting element andopposite to it.
 6. The device of claim 5, wherein the at least onedeflecting element includes at least one bulge, and the indentation isconfigured in a shape corresponding to that of the at least one bulge.7. The device of claim 1, wherein a forward part of the at least onechannel is offset in relation to a rear part, parallel to the main flowdirection.
 8. The device of claim 1, wherein at least one channelincludes at least one outlet opening having at least one oil rejectiongrid.
 9. The device of claim 1, wherein: the at least one channel isdivided into an inlet channel, a deflection channel, and an outletchannel; and the at least one channel includes an inlet opening, whichthe inlet channel adjoins and which the deflection channel adjoins, intowhich the medium flows from the inlet channel and is deflected to flowthrough the outlet channel to at least one outlet opening on an outersurface of the measuring housing that discharges into the line.
 10. Thedevice of claim 1, wherein the at least one deflecting element isconfigured to protect the at least one measuring element from theparticles and liquids.
 11. The device of claim 1, wherein a portion ofthe measuring housing is configured to house at least one analyzingelectronics.
 12. The device of claim 1, wherein the device is arrangeddownstream of at least one obstruction configured to regulate the flowto the at least one channel.
 13. The device of claim 1, furthercomprising: at least one tapering element configured to accelerate theflow in the at least one channel.
 14. The device of claim 1, wherein theat least one deflecting element is formed by at least one bulge on atleast one edge surface of the channel.
 15. A device for determining atleast one parameter of a medium, the medium including a gas-particlemixture of intake air for an internal combustion engine and flowing in aline along a main flow direction, the device comprising: a measuringhousing arranged in the line; at least one channel arranged in themeasuring housing and formed by edge surfaces that completely surroundthe channel; at least one measuring element located in the at least onechannel, surrounded by the edge surfaces of the, and around which themedium flows; and at least one deflecting element to deflect particlesand liquids that is arranged in the measuring housing in the at leastone channel, upstream from the measuring element, wherein the at leastone deflecting element is formed by at least one rejection grid.
 16. Adevice for determining at least one parameter of a medium, the mediumincluding a gas-particle mixture of intake air for an internalcombustion engine and flowing in a line along a main flow direction, thedevice comprising: a measuring housing arranged in the line; at leastone channel arranged in the measuring housing and formed by edgesurfaces that completely surround the channel; at least one measuringelement located in the at least one channel, surrounded by the edgesurfaces of the channel, and around which the medium flows; and at leastone deflecting element to deflect particles and liquids arranged aroundthe measuring housing, upstream from the measuring element, wherein theat least one channel includes the edge surfaces having at least twoparts, and a first part of the at least one channel is formed by asleeve arranged on the measuring housing.
 17. The device of claim 16,further comprising: at least one rejection grid arranged in the sleeve.18. A device for determining at least one parameter of a medium, themedium including a gas-particle mixture of intake air for an internalcombustion engine and flowing in a line along a main flow direction, thedevice comprising: a measuring housing arranged in the line; at leastone channel arranged in the measuring housing; at least one measuringelement located in the at least one channel, and around which the mediumflows; and at least one deflecting element to deflect particles andliquids is arranged one of around and in the measuring housing at leastone channel, upstream from the measuring element; wherein the at leastone channel is divided into an inlet channel, a deflection channel, andan outlet channel; wherein the at least one channel includes an inletopening, which the inlet channel adjoins and which the deflectionchannel adjoins, into which the medium flows from the inlet channel andis deflected to flow through the outlet channel to at least one outletopening on an outer surface of the measuring housing that dischargesinto the line; and wherein at least one pulsation channel adjoins the atleast one outlet opening.
 19. The device of claim 18, wherein the atleast one pulsation channel includes at least one oil rejection grid.20. The device of claim 18, wherein the at least one pulsation channelis configured to reduce a backflow.
 21. A device for determining atleast one parameter of a medium, the medium including a gas-particlemixture of intake air for an internal combustion engine and flowing in aline along a main flow direction, the device comprising: a measuringhousing arranged in the line; at least one channel arranged in themeasuring housing; at least one measuring element located in the atleast one channel, and around which the medium flows; and at least onedeflecting element to deflect particles and liquids is arranged one ofaround and in the measuring housing at least one channel, upstream fromthe measuring element; wherein the at least one channel includes a wallhaving an indentation pointing outward at approximately a same axiallength as that of the at least one deflecting element and opposite toit; and wherein the indentation is configured to collect the particlesand liquids.
 22. A device for determining at least one parameter of amedium, the medium including a gas particle mixture of intake air for aninternal combustion engine and flowing in a line along a main flowdirection, the device comprising: a measuring housing arranged in theline; at least one channel arranged in the measuring housing; at leastone measuring element located in the at least one channel, and aroundwhich the medium flows; and at least one deflecting element to deflectparticles and liquids is arranged one of around and in the measuringhousing at least one channel, upstream from the measuring element;wherein the at least one channel is serpentinely shaped.